Vacuum your carpet weekly so fine particulate matter (dust, dirt, etc.) does not get ground deeper into the carpet fiber. Your carpet will last longer.

Some carpet comes with factory protector applied to it. Yet you should apply carpet protector to you carpet at least once a year or every time you have your carpet cleaned to help your carpet last longer.

Always hire a carpet cleaner that uses the best non-toxic cleaning products (environmentally safe for humans and pets) and top-of-the-line van-mounted equipment.

When buying carpet always pick a dense carpet as the dirt, dust, particulate matter, etc. can't get knocked down deeper and deeper down into the carpet. The result is longer life out of your carpet and better cleaning.

Even though your carpet may not look dirty, chances are, it probably is, especially if it is a darker color which hides dirt better. Lighter colors may have a darker tint from dirt build up but you may still not notice it.

Cleaning the carpet yearly will also help to reduce the traffic lane build up and keep your carpet looking nice for many years to come.

If your carpet is neglected and not cleaned yearly it will be much harder to get clean, especially if the traffic lanes start to build up for years. They are very hard to alleviate, which shortens the life of your carpet.

Be careful with store bought spot and stain removers as many of these products will set the stain, or lock it in so that you can't remove it. There are many different kinds of carpet fibers and you must make sure you are putting the right products on the right kind of carpet fiber or you will do more damage than good to the carpet.

Hire a professional carpet cleaner. Don't get duped by discount coupons offering $5 - $15 dollars a room cleaned.
Those companies always charge extra for pre-spray, about 25 - 30 cents a square foot, or they don't use pre-spray at all which greatly reduces the ability to remove dirt, dust, particulate matter, etc., leaving your carpet dirty.
Many of these companies also charge extra for traffic lanes, or common spots that don't come out since they don't use a pre-spray. A pre-spray helps to break down dirt, dust, spots, and particulate matter thus getting your carpet as clean as possible.
Many of these companies also have problems with spots and traffic lanes reappearing, which is referred to in the industry as wicking, which means as the carpet dries the spots and traffic lanes wick back to the top of the carpet. In order to eliminate wicking problems carpet cleaners should always use a pre-spray,extract the pre-spray, and always do dry passes which helps to suck as much moisture out of the carpet as possible this way your carpet should dry in about one to four hours depending on what kind of carpet you have.